The common histologic findings in these patients were

2018-11-15

The common histologic findings in these patients were follicular hyperkeratosis with arrector pili myositis. However, hyperkeratosis unrelated to hair follicles has also been described. Although there were no demonstrable follicular hyperkeratosis or arrector pili myositis, due to the biopsy site of the palm in our patient, parakeratosis in the horizontal and vertical arrays suggested features of PRP. The cornoid lamella found on histopathology in our patient is unusual, although it may be an incidental finding and have no clinical significance. However, there was one reported case of Wong type dermatomyositis showing clinical and histologic features highly suggestive of porokeratosis. The incidence of PRP and porokeratosis-like lesions occurring together is unknown, because they are usually asymptomatic and can be easily overlooked on cutaneous examination.
Our patient developed symptoms of dermatomyositis and rheumatoid arthritis, satisfying the criteria of overlap syndrome: at least two connective tissue diseases occurring at the same or at different times in the same patient. An association of polymyositis/dermatomyositis with RA has long been established. Polymyositis/dermatomyositis can develop at any stage of RA. In recent years, genomic studies have shown marked overexpression of type I interferon inducible genes in the peripheral blood of patients with systemic lupus erythematosus, dermatomyositis, polymyositis, multiple sclerosis, rheumatoid arthritis, systemic sclerosis, and Sjögren\'s syndrome, indicating that these diseases share activation of a common type I interferon pathway.
Our patient also fulfilled the criteria of anti-t-RNA synthetase syndrome. This is a well-known overlap syndrome characterized by a specific autoantibody marker that usually has clinical manifestations milder than those observed in patients with any single connective tissue disease included in overlap syndrome. Patients who produce anti-Jo-1 order GDC-0152 less frequently display the classic manifestations of dermatomyositis. This may be the reason that our patient had fewer characteristic cutaneous features of dermatomyositis. About 60–90% of patients affected with anti-Jo-1 positive anti-t-RNA synthetase syndrome develop symmetric arthritis that can fulfill the 2010 American College of Rheumatology/ European League Against Rheumatism criteria for RA. Interstitial lung involvement has been described in 50–85% of patients with anti-Jo-1 antibodies. Our patient had arthralgia, arthritis, and myositis; he did not have a fever, Raynaud\'s phenomenon, dyspnea, or any other symptoms/signs of interstitial lung disease. Anti-Jo-1 antibody has often been associated with other antibodies, including anti-Ro/SSA and anti-La/SSB, which were also noted in our patient.
Introduction
Myopericytoma is a benign tumor composed of myoid-appearing oval to spindle-shaped cells with a concentric perivascular pattern of growth. The term myopericytoma was first proposed by Requena et al as an alternative designation for solitary myofibroma derived from myopericytes. The concept of perivascular myoid differentiation was established by Granter et al. It is characterized by a well-circumscribed, slow-growing, painless mass that arises most commonly in the dermis or subcutaneous tissue of extremities in adults. We describe a case of myopericytoma with unusual clinical presentation as scarring alopecia in a child.
Case report
A 14-year-old girl without any underlying disease presented with a 2-month history of an alopecic patch on her frontal scalp. Physical examination revealed a pink patch with hair loss and follicular plugging, measuring 2.5 cm × 1.5 cm (Figure 1). The initial impression was of discoid lupus erythematosus. Laboratory tests for lupus erythematosus and a lupus band test were negative. A skin biopsy specimen revealed a subcutaneous large vein-like structure surrounded by multiple small branching vascular spaces lined by spindled, stellate, and cuboidal cells. The overlying dermis was fibrotic with dilated vessels and a scanty number of hair follicles remained (Figure 2A–C). An immunohistochemical study showed that the majority of tumor cells were positive for smooth muscle actin (SMA) and h-caldesmon, but negative for desmin. Positive CD-31 staining of the lining cells of the peritumoral vascular spaces suggested that the tumor was located in a dilated vessel (Figure 3A–D). The lesion was believed to be an intravascular myopericytoma. The alopecic patch was excised and no recurrence was observed 2 years later.